#include<iostream>

using namespace std;

int main(){
    float a,b,h;
    cin >> a;
    cin >> b;
    cin >> h;
    if(b < a){
        int c = a;
        a = b;
        b = c;
        cout << "Yes" << endl;
    }
    else{
        cout << "No" << endl;
    }
    printf("%.1f",((a+b)*h)/2.0);
}